The relationship of dyspnea to function and quality of life in systemic sclerosis

Murray Baron ^1*, Evelyn Sutton ², Marie Hudson ³, Brett Thombs ³, Janet Markland ⁴, Janet E Pope ⁵, David Robinson ⁶, Niall Jones ⁷, Peter Docherty ⁸, Maysan Abu-Hakima ⁹, Sharon Leclercq ⁹, Douglas Smith ¹⁰ and Jean-Pierre Mathieu ¹¹

¹ Jewish General Hospital, Canada
² Dalhousie University, Canada
³ McGill University, Canada
⁴ University of Saskatchewan, Canada
⁵ The University of Western Ontario, Canada
⁶ University of Manitoba, Canada
⁷ University of Alberta, Canada
⁸ Moncton, Canada
⁹ University of Calgary, Canada
¹⁰ University of Ottawa, Canada
¹¹ University of Montreal, Canada

^* To whom correspondence should be addressed. E-mail: mbaron{at}rhu.jgh.mcgill.ca.

Accepted 12 August 2007

Abstract

Objective: Up to 50% of patients with systemic sclerosis (SSc) have complaints of dyspnea. We evaluated the independent contributions of dyspnea to function and health related quality of life (HRQoL) in SSc and also assessed the contributions of pulmonary hypertension, measured by the pulmonary artery systolic pressure (PASP), and interstitial lung disease, measured by the forced vital capacity (FVC), to dyspnea.

Methods: We assessed dyspnea, PASP, FVC, function and HRQoL in a cohort of unselected patients with SSc. Multiple linear regression was used to assess the independent contributions of dyspnea, PASP and FVC to function and HRQoL, after controlling for possible confounding variables.

Results: 194 patients with a mean disease duration of 11.6 years were studied. Dyspnea was a significant independent predictor of function and HRQoL. A model including age, gender, disease duration, disease severity and dyspnea explained 33.3%, 10.6%, 39.2% and 29.4% of the variance of the Stanford Health Assessment Questionnaire, the SF-36 mental component summary score, the SF-36 physical component summary score and the World Health Organization Disability Assessment Schedule II. Both PASP and FVC were significant independent predictors of dyspnea but only 21.9% of the variance in dyspnea was explained by age, gender, disease duration, FVC and PASP. The FVC was a significant independent predictor of function and HRQoL.

Conclusion: In an unselected population of SSc patients, dyspnea is a very important contributor to function and HRQoL. Interstitial lung disease, as measured by the FVC, contributes significantly to the sense of dyspnea, function and HRQoL in SSc. Pulmonary hypertension, assessed echocardiographically by the PASP, predicts the degree of dyspnea but not function and HRQoL in SSc.

Keywords: dyspnea, hypertension, pulmonary, lung diseases, interstitial, quality of life, scleroderma, systemic

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